PostGIS is a spatial database extension for PostgreSQL. PostGIS complies with the OpenGIS "Simple Features for SQL" specification, and provides high-performance spatial SQL access to GIS objects in the database.
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS). As such, it aims to contain the complete functionality of JTS in C++. This includes all the OpenGIS "Simple Features for SQL" spatial predicate functions and spatial operators, as well as specific JTS topology functions such as IsValid().
Ming is a library for writing SWF (Flash) format files. It includes high-level functions which abstract away mundane specifics of the file format and PHP (and now Python/Zope, Ruby, and c++) module code which wraps the library into handy objects.
SINS (Sins Is Not Snake) is a nibble-like game written in C and with modular user interface (X, curses, vgalib available)
and players (AI,human).
If you're a C programmer you can try
to make your own ai players and make
them play against mine :)